In the webmail version, I can use [CTRL] + [+] to increase the zoom of the windows and so have bigger font size of the UI. There is even an option in the Settings / General / Appearance / to increase or decrease the size of the fonts of the UI/screen.

In my case (Debian 8.7 64bits), Zimbra Desktop UI is set to a very very small size, meaning font of the UI are very small. If I use [CTRL] + [+] or [CTRL] + [roll of the mouse]... nothing happen. And there is no option in the settings. So I only have to use a magnifying glass

Is there a way to increase the fonts of the screen / UI in Zimbra Desktop ?